The present invention relates to plant-derived high molecular weight substances which have potent anti-HIV activity. The human immunodeficiency virus (HIV) is the causative agent associated with AIDS (acquired immune deficiency syndrome), ARC (AIDS-related complex) and related diseases. A distinguishing feature of HIV is its selective cytotoxicity for helper T lymphocytes. Severe and diverse aberrations of the immune system significantly reduce the host defense against various opportunistic infections, resulting finally in a host death.
Nowadays, many anti-HIV agents including Krestin and Lentinan have been isolated from plants and chemically synthesized. However, the effect of most of these agents are generally weak and they have severe side effects.
In order to explore new type of anti-HIV substance, the present inventors have compared the anti-HIV activity of various plant components. The present inventors have found potent anti-HIV activity in the antitumor substances obtained from aqueous alkaline extract of pine cone. The substances with the most potent anti-HIV activity was named as KS-6 and KS-7.